There are times when it is desirable to detect the times of occurrence of certain actions. Commercial trash haulers sometimes receive complaints from customers that their refuse containers have not been emptied according to their agreed schedules. The trash hauling companies usually require their drivers to keep records of the service calls they make for various business purposes, including documentation that the required calls to customers on a route have been made. The driver may keep such records by manually filling in an activity log, punching pertinent information into a computerized logging device, or the like.
Unforeseeable events may prevent a driver from servicing a customer at a given time, such as traffic tie ups, mechanical breakdown of equipment, inclement weather, or the intervention of holidays. Other, less innocent, factors may also interfere with the process. For example, a customer may have had his container emptied on schedule, only to be refilled by someone other than the rightful 30 customer and without the customer's knowledge. In other cases, a customer may try to obtain more frequent service than contracted for by refilling his timely emptied container and then claiming that it was not emptied on schedule. Finally, an unconscientious driver may log-in service calls not actually made, out of laziness, dishonesty, or some other motive.
In order to avoid impugning the honesty of a customer or a driver without objective documentation of service rendered or proof of cheating, the trash hauling company often has no choice but to send a truck on a special trip to empty the customer's container at a non-scheduled time. Such special trips increase operating costs which must be born by other customers or the company. However, the effort required to investigate and prove that someone is cheating in the transaction also has its costs. What is needed is a mechanism for objectively indicating when a particular refuse container was emptied which does not rely on the honesty of a customer or a driver. Such a mechanism must be simple and economical, rugged enough to survive extremes of its operating environment, and tamperproof.